Embodiments of the present invention provide methods and systems for determining depth of a wireline in a borehole penetrating an earth formation. In particular, but not by way of limitation, the invention describes the use of passive and/or active agents—such as radio frequency identification (“RFID”) tags, transponders, highly conducting materials, highly conducting regions and/or the like—disposed along the length of the wireline to provide for interaction with and/or response to a device capable of remotely interacting with the passive and/or active agents—such as a transceiver, antenna, signal processing circuit, coil with an applied alternating current and/or the like—to determine the length of the wireline in the borehole. The agents disposed along the wireline may be responsive/reactive to, in effect, provide for communication between the wireline and the remote device. Embodiments of the present invention provide for the use of responsive/interactive agents that are robust and may be coupled with the wireline and in particular, but not by way of limitation, may be coupled under the armoring layer of the wireline to provide that the of responsive/reactive agents maintain their responsiveness/reactiveness when used in the field.
In an embodiment of the present invention, transponders are distributed along the wireline at predetermined intervals. The transponders may communicate with a device configured to interact with the transponders—such as an antenna, transceiver, signal processor circuit or the like—as the transponders pass a measurement point. The measurement point may be any location selected for measuring the movement of the wireline into and/or out of the borehole and the device capable of interacting with the transponder may be configured to provide for the limiting of interaction with only those transponders at the measuring point or in close proximity thereto. In some embodiments, the transponders may be either passive or active RFID tags and the interaction device may be a radio frequency transceiver, antenna combined with a signal processor and/or the like. In other embodiments, materials with electrical conductivity higher than the wireline—i.e., copper, gold, silver, highly conducting metals or the like—or regions of the wireline treated to have highly electrically-conducting properties—may be disposed along the length of the wireline to provide for interaction with the interactive device—which may be a coil of conductive wire supplied with an alternating current. For purposes of this invention the terms “conducting” and “electrically conducting” may be used interchangeably.
In certain aspects, the highly conductive materials and/or highly conductive regions may be grouped together and logically arranged on the wireline to provide for communication of information from the wireline to the interactive device. The information stored in the grouping/arrangement of the highly conductive materials and/or highly conductive regions may uniquely identify the group of highly conductive materials and/or highly conductive regions to the interactive device and/or a distance from a specific location on the wireline to the position of the group of highly conductive materials and/or highly conductive regions. In other aspects, the responsive/interactive agents on the wireline may be RFID tags that may store and provide data to the interactive device—such as a unique RFID tag identification and/or the distance from a specific location on the wireline to the position of each of the RFID tags. In some embodiments, the transponders, conducting material/regions and/or the like may be disposed along the wireline when the wireline is under tension/temperature conditions that may mimic the conditions for the wireline when used in practice.
In certain embodiments of the present invention, measurements from the passive and/or active agents may be combined with measurements from an odometer wheel and/or a set of odometer wheels in frictional contact with the wireline. In such embodiments, distances between the locations of the passive and/or active agents located on the wireline may be determined. In further embodiments, the wireline may be configured to include a fiber optic cable in combination with the passive and/or active agents. As such, time of flight measurements of an optical pulse passed down the fiber optic may be measured and stretch of the wireline may be measured. In yet further embodiments, measurements from the passive and/or active agents and stretch measurements from the time of flight of the optical beam may be combined with measurements from the odometer wheel(s) to provide a system for measuring wireline depth in the borehole that may be both robust and accurate.
In the appended figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.